The present invention relates generally to double conversion receivers, and, more particularly, to a dual-carrier, double conversion receiver for a multi-carrier communication system.
Conventional wireless communication systems transmit data to users on a single carrier. To meet the demand for wireless high-speed data services, carrier aggregation is being introduced in Long Term Evolution Advanced (LTE-A) networks. Carrier aggregation supports wider transmission bandwidths by allowing simultaneous transmission on multiple carriers. Multicarrier systems, such as LTE-A, offer advantages over conventional single carrier systems such as higher data rates, reduced latency, and improved support for Quality of Service (QoS).
A number of multi-carrier receiver architectures are possible. One solution is to provide separate receiver paths in the analog front-end. For adjacent or sufficiently close carriers, a first local oscillator can be used to down-convert both carrier signals from radio frequency to an intermediate frequency, and a second local oscillator can be used to down-convert the intermediate frequency signal to baseband. However, the use of two receiver paths in the analog front-end requires duplication of components, which increases cost, power consumption, and space requirements.
A single receiver front-end can be used to receive both carriers. A first local oscillator may be used to down-convert both carrier signals from radio frequency to an intermediate frequency and a second local oscillator to down-convert the intermediate frequency signals to baseband. The carrier signals are separated during the down-conversion to baseband. While this approach reduces the number of components, two local oscillators are still required: one for the down-conversion to the intermediate frequency and one for the down-conversion to baseband.
Despite advances in radio receiver architecture, there remains a need for further reduction in radio frequency components to meet increasing consumer demand for compact mobile devices with long battery life.